Paper manufacture



Patented June 22, 1931 UNITED STATES PATENT OFFICE A PAPER MANUFACTURE Harold Robert Rafton, Andover, Mass., assignor to Raffold Process Corporation, a corporation of Massachusetts No Drawing. Application May 7, 1934, Serial No. 724,453. In Canada April 16, 1934 22 Claims.

- will modify the characteristics of the paper so produced.

A further object is to provide a simple method for the manufacture of sized paper filled with alkaline filler.

A further object is to provide a method for manufacturing paper filled with alkaline filler, substantially unsized but possessing special characteristics.

A further object is to provide a method for the manufacture of paper filled with alkaline filler whereby there is imparted to the paper improved characteristics in respect to inertness, ink receptivity, pliability, folding qualities, strength, and the like.

A further object of this invention is the paper filled with alkaline filler manufactured by such method.

Other objects and advantages of this invention will become apparent during the course of the following description.

In my copending application Serial No. 487,377, filed October 8, 1930, I have disclosed and claimed the application to a fibrous web containing alkaline filler of thermoplastic material dissolved in,

In my copending application Seriala solvent. No. 609,555, filed May 5, 1932, Ihave disclosed and claimed the application to a fibrous web containing alkaline filler of non-thermoplastic material dissolved in a solvent. In my copending application Serial No. 621,509, filed July 8, 1932, now Patent No. 1,957,474, issued May 8, 1934, of which the present application is a continuation in part; I have disclosed the application to a paper web containing alkaline filler of liquid or pasty material dissolved in a solvent, said material being substantially inert to alkaline filler, and there being an absence in said web of waxy material substantially inert to alkaline filler: however in said copending application, no claim is made to said method.

It is an object of the present application to I claim the method, and the product made by the method, disclosed in my last mentioned copending application; and also to make certain further disclosure, and claims based on such disclosure both as to method and product thereof.

I have found that if, in the manufacture of paper filled with alkaline filler, there be applied to a. web containing alkaline filler a substantially water insoluble organic liquid in solution in a solvent, very desirable results are obtained in certain cases. For example sized paper may be made in certain instances in which all or part of the sizing may be imparted by said liquid, or sized paper may be made in which the sizing may be imparted by other sizing agent but in which certain qualities other than sizing may be imparted by the liquid in question. Substantially unsized,

paper may also be made, in which the liquid in question acts to impart certain desired qualities.

In either unsized or sized paper filled with alkaline filler the chemical reactivity of the paper may be substantially reduced by treatment with substantially water insoluble organic liquid, the

liquid apparently serving to,inhibit the alkalinity of the alkaline filler. This is of material importance in certain cases, for example where the paper is to be used for lithographing or the like. Moreover the receptivity to printing ink may be enhanced by the presence of the liquid. Also the flexibility or pliability of the paper may be enhanced, its strength improved, its folding resistance increased, and the like. ,The action of the substantially water insoluble organic liquid in rendering the paper more inert probably by its enveloping action appears to be an important factor in imparting to the paper at least'some of the improved characteristics herein described.

.As will be apparent these improved qualities are very desirable in paper filled with alkaline filler,

and my novel improved method of producing same, together with the paper made therewith, represent a substantial improvement in the art.

In the preferred embodiment of my invention I provide a paper mix containing alkaline-filler, run the mix off on a web-forming device,-to the so-formed web I apply the substantially water insoluble organic liquid dissolved in a solvent, and then substantially remove the solvent content of the web.

I may use either water miscible or water immiscible solvents. In the case of water miscible solvents the solution may be applied to either the 1 wet or the dry web, but in the case of water immiscible solvents the solution is applied preferably to the already substantially dried web.

Whereas the solution may be applied to the paper web during the course of its formation at any point on the web-forming device, this however is not the preferred practice of my invention as I prefer to apply the solution subsequent to the web-forming device.

When awater miscible solvent is applied to a wet web, the heating of the web to drive off the water serves in general also to drive off the solvent, or if required additional drying capacity may be provided for driving off either all or substantially all-of the solvent which may remain in the web. Although heat, such as is supplied for example by driers or a hot gas,'is a convenient means of eliminating the solvent, such removal may be accomplished merely by exposure of the solution treated web to the atmosphere or other gas at ordinary temperature but the latter is usually a time consuming procedure. Reduced pressure is of considerable assistance in this connection and may be used alone or in connection with heat to remove the solvent and the associated water if there be such.

In the case of water immiscible solvent, the solution containing the same may be applied to the dried web as stated above and it may be subsequently removed either by exposing the so treated web to the atmosphere or other gas, or by the use of heat as above, or reduced pressure,

or both.

With either type of solvent, suitable means should preferably be provided for solvent recovery in the interest of economy.

' In the case where the solution is applied to the wet web, it may be most conveniently applied to the web while it is on the paper machine; and where it'is to be applied to thedry web it may be also satisfactorily applied on the paper machine; but in certain cases it is desirable to apply it as a separateprocess subsequent to the papermaking operation.

As will be apparent I may use solutions of va-.

rious strengths for various purposes, but in most cases I find it convenient to use a solution having a concentration of.,about 23-10% of the substantially water insoluble liquid therein. Likewise as will be apparent I may vary the amount of the substantially water insoluble liquid introduced into the web to suit conditions, but in general I find that from a fraction of 1% up to several percent on the weight of the finished paper usually produces a satisfactory product.

The application of the solution to the paper web may take place by means of any suitable applying device such as a trough, applying rolls,

brushes, sprays, or the like, but I prefer, when applying the solution to a wet web, to use an applying roll, and when applying it'to the substantially dry web to use a trough followed by squeeze rolls, or a spray. When the web is not actually immersed in the solution, application may be made to one or both sides as desired.

The application may take place at any desired point on the paper machine, but I have found it convenient when applying the solution to the wet web to apply the solution at the press rolls, preferably at the third press if the machinebe so equipped or later at the smooth rolls if desired.

'When applying it to the dry web, I prefer to apply it by suitable applying device at that point in the course of the drying where the sheet has been substantially deprived of its moisture. A paper machine equipped with a vacuum drier lends itself very readily for the carrying out of my invention as the application andrecovery of .the solvent may be carried out in connection therewith in a relatively simple manner; or an auxiliary vacuum drier may be employed subsequent to the main drying, whether or not the drying takes place originally with a vacuum drier.

However a very simple apparatus which may be satisfactorily employed is that disclosed in my copending application Serial No. 640,714 -filed November 1, 1932, which operates at substantially atmospheric or only slightly below atmospheric pressure. This is very economical apparatus to use as it is much less expensive than a vacuum drier.

However where it is not desired to recover the solvent, I may merely use a ventilating hood to remove the same.

As stated above I may make sized or unsized paper. Sized paper may be made from an unmix from which the paper is to be made, adding,

if desired, certain of the materials under conditions favoring the minimizing of the time and/or intimacy of contact of the constituents of the mix. This and other methods of sizing alkaline filled papers have been disclosed in a large number of my already issued patents and any one of these or other suitable methods may be used.

In the manufacture of substantially unsized paper, an unsized paper mix is preferably employed and this is run off on the paper machine and the web is then treated with a suitable substantially water insoluble organic liquid dissolved in a solvent.

One illustrative example of practicing my invention in the manufacture of unsized paper is to.

mix fibrous material with approximately 25-30% of its weight of alkaline filler, add about 1% alum preferably under conditions favoring the mini- 'mizing of the time of contact with the constituents of the mix, and run the same off on the paper machine. I then treat the web so formed with approximately of suitable substantially water insoluble organic liquid dissolved in a sol-.

Another illustrative example of manufacturing sized paper according to my method is to mix the pulp with approximately 25-30% by weight of alkaline filler, size the mix by the use of size such as rosin size, or other size such as paraflin emulsion, as desired, preferably employing minimizing procedures, and then run the stock off on the paper machine, treating the web thereon with approximately 1-1 of the suitablesubstantially water insoluble organic liquid in solution.

It is to be understood that the above formulas areillustrative only, and in no way limiting as my invention may be practiced with widely varying formulae and in a number of different ways.

There are a wide variety of substantially water insoluble organic liquids which I may use in the practice of. my invention. These may either be substantially inert to alkaline filler, or they may not be and thus may fall in the class known as cocoanut oil.

It is to be understood, however, in respect to liquids which are saponifiable, that such liquids are to be used only in the substantially unsaponified condition. Thus, when liquid reactive with alkali i. e. saponifiable liquid, is stated to be dis;- solvedin solvent, its presence therein is intended to be confined to that condition in which it is substantially unreacted upon by alkali.

As will be apparent the solvent must be chosen with regard to its ability to dissolve the liquid in question; its volatility, cost, action on metals, infiammability and the like. Examples of suitable water immiscible solvents are petroleum ether and gasoline, chlorinated hydrocarbons such as carbon tetrachloride and ethylenedichloride, benzol and the like; and of water miscible solvents, ethyl and methyl alcohols, and acetone.

Inasmuch as the organic liquids I employ are substantially water insoluble, naturally where I used the word solvent in connection with these materials, I mean to confine myself to-solvents other than water which are liquid or become liquid in use, although of course for example with certain water miscible solvents such as ethyl alcohol there may be present at times in the solvent used a certain amount of water, which water however does not act in the present instance as a solvent. I also mean further to restrict myself to such solvents as possess a vapor pressure sufficiently high, that is to say a sufficiently low boiling point, as to be capable of being substantially removed from the web by at least one of the herein described procedures at a temperature which will not be sufficiently high to substantially injure the web.

As the solution of the substantially water insoluble organic liquid is preferably applied continuously to the web, suitable means such as a pump should be employed for supplying the solution to employed. .As will be understood, of course, substantially water insoluble organic'liquids may vary in viscosity from very mobile liquids to highly viscous,

liquids which mayin certain cases even approach the pasty condition, and in many instances ,the

condition of the liquid is determined by thetemperature at which it is examined. For the pur-r pose of this specification I include inthe definition of liquid all materials of whatever degree of viscosity at ordinary temperatures from mobile liquidity to a relatively high state of viscosity, but mean to excludeanymaterial thatf-sso closely approaches the solidstate as to possess thermoplasticity. e ,7

By the practice of my invention I produce paper filled with alkaline filler, which'paper is substantially opaque or possesses a substantial degree of opacity, which is suitable for printing or other purposes, and which is similar in'appearance to, and by cursory observation is 'difilcult' todistin guish from, ordinary clay-filled paper of the same grade. My paper is unlike and should not be confused with papers saturated with oils or the like and which aretransparent or translucent, and in the claims the word paper is to be construed as being restricted to such papers as are not saturated or not substantially saturated with the liquid specified.

Where I use the word liquid" herein in reference to' substantially water insoluble organic material I mean to limit myself to liquids which do not have a vapor pressure sufficiently high spontaneously to evaporate to a substantial degree at ordinary or room temperature, or at a temperature to which paper may be subjected in the manufacturing process subsequent to the inclusion of such liquid in the paper web, (in the latter case of course meaning for the time it will be subjected thereto), as obviously the inclusion of any low boiling liquid would be of little or noavail owing to its substantial removal from the paper either spontaneously or by the heat to which the paper web containing such liquid was subjected.

By the term alkaline filler, I mean substantially water insoluble filler which when agitated in contact with freshly boiled distilled water, say for an hour, will impart a pH value to such water greater than 7.0, that is, which will be on the alkaline side of the neutral point. Among fillers included in this group may be mentioned calcium By the term "alkaline filler, I also intend to include fibrous material and/or other material such as paper coating constituents or the like containing one or more compounds of the character referred to, such as old papers or similar papers, broke or the like.

When I use the word paper herein, I use it in the broad sense to include products of manufacture of all types and of all weights and thicknesses, which contain as an essential constituent a considerable amount of prepared fibre and which are capable of being produced on a'Fourdrinier, cylinder, or other forming, felting, shaping or molding machine. 1

When I speak ofipaper as having an enhanced receptivity to printing ink orv the like, I do not mean that said paper necessarily satisfies any one specific test'such'as rate of water or oil penetration or'the like; but rather I mean broadly that, regardlessof the result of any specific test performed on said paper, the paper so characterized possesses improved printing qualities.

' Where in the claims I speak "of applying material to the fibrous web", unless theweb is specifically qualified as "dry, I mean of course that herein is, intended to mean a mix of various constituents including fibre from which paper may be made either directly or after the addition of other ingredients.

While I have described in detail the preferred embodiment of my invention, it is to be'understood that the details of procedure, the proportions andkinds-of ingredients, and the arrangement of steps may be widely varied without departing from the spirit of my invention or the scope of the subjoined claims.

I claim:

1. The step in a method of manufacturing paper filled with alkaline filler comprising distributing in a fibrous web containing alkaline filler substantially water insoluble organic liquid by means of a vehicle comprising a solvent in which said liquid is soluble.

2. The steps in a method of manufacturing paper filled with alkaline filler comprising applying to a fibrous web containing alkaline filler substantially water insoluble organic liquid dissolved in solvent, and subsequently substantially removing the solvent content of said web.

3. The step in a method of manufacturing paper filled with alkaline filler comprising applying to a substantially dry fibrous web containing alkaline filler substantially water insoluble organic liquid dissolved in solvent.

4. The steps in a method of manufacturing paper filled with alkaline filler comprising applying to a substantially dry fibrous web containing alkaline filler substantially water insoluble organic liquid dissolved in solvent, and subsequently substantially removing the solvent content of said 'web.

5. The steps in -a method of manufacturing paper filled with alkaline filler comprising applying to a fibrous web containing alkaline filler substantially water insoluble organic liquid dissolved in solvent, and subsequently substantially removing the solvent content of said web by reduced pressure.

' 6. The steps in a method of manufacturing paper filled with alkaline filler comprising applying to a fibrous web containing alkaline filler substantially water insoluble organic liquid dissolved in solvent, and subsequently substantially removing the solvent content of said web by heat.

'7. The steps in a method of manufacturing paper filled with alkaline filler comprising applying to a fibrous Web containing alkaline filler sub-' stantially water insoluble organic liquid dissolved in solvent, and subsequently substantially removing the solvent content of said web by reduced pressure and heat.

8. The step in a method of manufacturing paper filled with alkaline filler comprising applying to a fibrous web containing alkaline filler substantially water insoluble substantially unsaponifiable organic liquid dissolved in solvent.

9. The steps in a method of manufacturing paper filled with alkaline filler comprising applying to a fibrous web containing alkaline filler substantially water insoluble substantially unsaponifiable organic liquid dissolved in solvent, and subsequently substantially removing the solvent content of said web.

10. The step in a method of manufacturing paper filled withalkaline-filler comprising applying to a fibrous web containing alkaline filler substantially water insoluble saponifiable organic liquid dissolved in solvent 11. The steps in a method of manufacturing paper filled with alkaline filler comprising applying to a fibrous web containing alkaline filler substantially water insoluble saponifiable organic liquid dissolved in solvent, and subsequently substantially removing the solvent content of said wen 12. The method of diminishing the chemical reactivity of .a paper web filled with alkaline filler, comprising treating said web with a'substantially water insoluble organic liquid dissolved in solvent, and then substantially eliminating said solvent from said web. 13. Paper filled with alkaline filler, comprising fibrous material, alkaline filler, and saponifiable vegetable oil, the particles of said filler being characterized by having a coating of said oil -thereon, said coating of oil having been deposited ponifiable vegetable oil in an amount sufiicient to impart sizing effect to said paper, the particles of said filler being characterized by having a coating of said oil thereon, said coating. of'oil having been deposited thereon out of solution in a solvent. Y

16. Paper filled with alkaline filler, comprising fibrous material, alkaline filler, sizing, and saponifiable vegetable oil, the particles of said filler being characterized by having a coating of said oil therecn, said coating of oil having been deposited thereon out of solution in a solvent.

17. Paper filled with alkaline filler, comprising fibrous material, alkaline filler, rosin sizing, and saponifiable vegetable oil, the particles of said filler being characterized by having a coating of said 011 thereon, said coating of oil having been deposited thereon out of solution in a solvent.

of solution in a solvent.

19., Substantially unsized paper filled ;with alkaline filler,'comprising fibrous material, alkaline filler, and substantially water insoluble saponifiable organic liquid in an amount insufiicient to impart sizing efiect to said paper, the particles of said filler being characterized by having a coating of said liquid thereon, said coating of said liquid having been deposited thereon out of solution in a solvent. I

20. Sized-paper filled with alkaline filler, comprising fibrous material, alkaline filler, and sub: stantially water insoluble saponifiable organic liquid in an amount sufiicient to impart sizing efiect to said paper, the particles of said filler be.- ing characterized by having a. coating of said liquid thereon, said coating of said liquid having been deposited thereon out of solution in a solvent.. g

21. Paper filled with alkaline filler, comprising fibrous materiaL'a-lkaline filler, sizing, and-sub- 4 stantially water insoluble saponifiable organic liqby having a coating of said liquid thereon, said coating of said liquid having been deposited thereon out of solution in a solvent.

22. Paper filled with alkaline filler, comprising fibrous material, alkaline filler, rosin sizing, and substantially water insoluble saponifiable organic liquid, the particles of said filler being characterized by having a coating of said liquid thereon, said coating of said liquid having been deposited thereon out of solution in a. solvent.

HAROLD ROBERT RAFTON. 

